Electronic phase comparator sensing means



Oct. 1 1968 J13, NOBLE ET AL ELECTRONIC PHASE COMPARATOR SENSING MEANSOriginal Filed Oct. 4, 1960 INVENTORS.

United States Patent 3,404,288 ELECTRONIC PHASE COMPARATOR SENSING MEANSJack I). Noble, Lafayette, Calif., and William Fleming, 2024 th Ave.,Oakland, Calif. 94606; said Noble assignor to said Fleming Originalapplication Oct. 4, 1960, Ser. No. 60,510, now Patent No. 3,259,199,dated July 5, 1966. Divided and this application Oct. 21, 1965, Ser. No.516,811

2 Claims. (Cl. 307-232) ABSTRACT OF THE DISCLOSURE An electronic sensingdevice for providing an output signal responsive to the comparisonbetween two input signals is disclosed. The device comprises atransformer with power leads from taps thereon adapted to carry currentof opposite phase relationship, a rectifying means of opposite phasesensitivity in each power lead forming an intermittent pulsing voltageof opposite phase with each power lead being connected to a relaytransistor. Means are provided for receiving two separate input signalsof alternating current in bucking relationship and providing a resultantalternating current which is amplified. The positive pulses of thisresultant alternating current are filtered out and the negative pulsesare applied to the bases of the relay transistors. When the negativeinput impulse of the amplified alternating current is applied to thetransistors it will be in-phase with and match the intermittent pulseson one of them, depending on the relative strength of each buckingvoltage, thereby producing an output from the inphase transistor.

This application is a divisional application of the parent applicationSer. No. 60,510, filed on Oct. 4, 1960, and now US. Patent No.3,259,199.

This invention relates to an electronic sensing device particularlyadaptable for use in a batching control system, in which severalingredients are weighed out simultaneously in any of various preselectedcombinations and proportions.

In its novel arrangement of elements, the batch system of the parentapplication employs highly accurate potentiometers on which resistancevalues are set in advance to represent the weight of each ingredient ofa predetermined batch formula. A servo-loop system is used in settingthese potentiometers. When the preset potentiometers are switched intothe batching circuit, a master scale-drum potentiometer is then drivenbya motor in the servo-loop system. The motor driving the masterscale-drum potentiometer is connected through the servo-loop system to aservo-transmitter driven by the dial scale on each of theweigh-batchers, and these scales thus act through the servo-loop systemto send a voltage signal from the scaledrum potentiometer which isproportional to the actual amount of material in a weigh-hopper at anygiven instant. To control the cutoff of material flowing into theweigh-hopper, voltages through the preset potentiometers are comparedelectrically With the voltage obtained through the master scale-drumpotentiometer. The general object of the present invention is to providea novel batchbrain or electronic sensing device for accomplishin thiscontrol function. In the case of the batching system the reaction ofthis batch-brain to the comparison of the voltages through the presetpotentiometer and the master scale potentiometer controls the closing ofthe inlet cutoii valve to the particular weigh-hopper and energizes aswitch to close a circuit to the next weigh-hopper to start theweighing-out of the next ingredient. This cut-off feature of thisbatch-brain or sensing device is accurate and reliable, and is providedin addition to the constant visual reference of the weight of eachmaterial being weighed out, afforded by the scale indicator.

Another object of the present invention is to provide a novel electronicsensing or switching means for energizing circuits which is responsiveto an unbalance of two voltages, one obtained by passing current througha preset resistance and the other by passing current through aresistance that varies according to some other variable such as theactual weight of material in a weigh-hopper. This switching means can beadapted to provide a visual indication of an overweight or underweightcondition in a particular hopper.

Other objects and advantages will appear from the following descriptionof the invention and the drawing which is a detailed circuit diagram ofan electronic sensing device embodying the principles of the presentinvention.

Referring to the sole drawing, a schematic circuit diagram is shown ofan electronic sensing device or batchbrain 112 which may be particularlyadaptable for use in a materials batching control system. Power (e.g.,26 volts, 400-cycle), is supplied to the device 112 through a pair ofleads 66 and 67 from a center-tapped power transformer (not shown), thecenter-tap 63 being grounded so that each of the leads 66 and 67supplies an alternating current of equal voltage. However, since thesevoltages are supplied from opposite ends of the transformer, they are inan opposite-phase relationship. As shown, the first power-lead 66branches at a junction 550. One lead 551 from the junction 550 goesthrough a diode-rectifier 552 to a junction 553, from which a lead 554extends to ground through a first filter-condenser 555 (e.g., 10microfarads, 25 volts). The junction 553 also is connected to aresistance capacity filter-network comprising a first resistance 556(e.g., 1000 ohms), and a second larger resistance 557 (e.g., 15,000ohms), between which is a junction 558 from which a lead 559 extends toground through a second filter-condenser 560 (e.g., 10 microfarads, 25volts). The resistor 557 is connected to a junction 561, which isconnected by a lead 562 to the collector 563 of an NPN-type transistor564 (e.g., 2N169A).

From the junction 558 between the resistors 556 and 557, there is also alead 565 connected through a relatively large resistance 566 (e.g.,100,000 ohms) to a junction 567, from which another lead 568 passes toground through a somewhat smaller resistance 569 (e.g., 3900 ohms) toform a voltage-dividing network. This network affords a bias-voltage tothe base of the transistor 564 by way of the lead 300 that is connectedto the secondary- Winding of the input or coupling-transformer 302; thelead 301 is connected through an isolation-resistor 570 (e.g., 470 ohms)and a junction 571. Simultaneously, a considerably higher voltage isbeing applied on the collector 563 of the transistor 564 through thelead 562 and the 15,000-ohms resistance 557.

A feed-back or regeneration-circuit is provided by connecting thejunction 571 through a condenser 572 (e.g., 10 microfarads, 25 volts) toa junction 573. The emitter 574 from the transistor 564 is connected bya lead 575 to the junction 573, from which point a lead 576 goes througha resistance 577 (e.g., 1000 ohms) to ground and a lead 578 goes througha condenser 579 (e.g., 40 microfarads, 4 volts) to ground. The condenser579 serves to bring the transistor 564 into its proper operating rangeso that it will function as an audio-amplifier, as will be describedbelow.

The junction-point 561 is also connected by a lead 580 to ajunction-point 581. From this junction 581 a firstlead 582 goes througha coupling-condenser 588 (e.g., 10 microfarads and 10 volts) to the base583 of a first-relay transistor 584, and a second-lead 585 is connectedthrough a coupling-condenser 589 (e.g., l0 microfarads and 10 volts) tothe base 586 of a second-relay transistor 587.

The other incoming lead 67 to the batch-brain 112 from thepower-transformer 58 supplies voltage through a rectifier 602 which isgrounded through a voltage-stabilizing resistance 603 (e.g., 10,000ohms) :and connected by a lead 604 to a junction 605. The junction 605is connected through a resistance 606 (e.g., 3300 ohms) to the collector607 of the second-relay transistor 587.

The relay-transistors 504 and 587 each have an emitter 608 or 609, withleads 610 and 611 connected through a stabilizing-resistance 612 toground.

From the collectors 601 and 607 of the relay-transistors 584, 587, leads613 and 614 are connected, respectively, to the underweight andoverweight relays 304 and 303. The junction-point 599 is also connectedto the underweight-relay 304 by a lead 615, a diode 616, and a lead 617.Similarly, the junction 605 is connected to the overweight-relay 303 bya lead 618, diode 619, and lead 620. The diodes 616 and 619 allowpassage of negative supply-voltage to their respective relay-coils 304and 303. Additional diodes 621 and 622 respectively between the leads617 and 613 and between the leads 620 and 614, which serve to quench theback-EMF-surge which is caused when the relays 304, 303 arede-energized. A large back-surge from the collapse of the magnetic fieldof these relays would damage the transistors 584 and 587 if the diodes621 and 622 were not there. Between each of the pair of leads 617 and613 and the leads 620 .and 614 is connected a condenser 623 or 624(e.g., 10 microfarads, 25 volts), each of which serves as a filteringmeans to prevent chatter at the frequency of the supply-voltage.

To understand the unique function of the sensing device 112 of thepresent invention, it must be understood that a phase-relationshipexists between the input from the power-transformer and the input fromthe coupling-transformer 302. Two voltages are supplied to theprimarywinding of the transformer 302.

Thus at any given instant, if one such voltage supplied to the primaryof the transformer 302 is greater than the other, one end of theprimary-winding will be (plus) and the other end will be (minus). Forexample, if at that time a master-scale potentiometer of a batchingcontrol system is set at its zero-weight, no resistance condition, andif a material-potentiometer is set at any point upon the scale, forexample at volts, then the end of the primary-winding connected to thematerial-potentiometer becomes positive and the other end of the primaryconnected to the scale-potentiometer becomes negative. This is exactlywhat happens in an underweight situation. Conversely, if thescale-potentiometer voltage is greater than the material-potentiometervoltage, an overweight condition arises, and the current at the samerelative instant flows in the opposite direction through theprimary-winding; thus the phase in the secondary-winding of the transformer 302b is reversed.

In the operation of our sensing device 112, AC-voltage is suppliedequally through its output-leads 66 and 67 from a power transformer andin the device 112 the current in these leads is rectified by the diodes596 and 602 to form a pulsating DC-voltage. Since the voltage from theopposite end-leads of a transformer are always in opposite-phaserelationship, the pulsating DC produced is applied to the transistors584 and 587 in alternate negative half-wave cycles. In other words, thepulses of DC-voltage arrive at the collectors 601 and 607 of thetransistors 584 and 587 at exactly the opposite times. Thus, forexample, at a particular instant when the voltage in the lead 66 isnegative, the voltage in the lead 67 will be positive. Therefore, anegative-voltage will appear at diode 596 and on the collector 601,while the positive voltage coming in via the lead 67 will be blocked bythe diode 602 and cannot get through; so there will be no voltageapplied to the collector 607 of the transistor 587. On the nexthalf-cycle, the polarities of the leads 66 and 67 will be reversed, andthe transistor 587 will be supplied with voltage and the transistor 584will not.

As described above, the incoming AC-signal supplied through leads 300and 301 of the c-oupling-transformer 302 has one-half of its pulsepositive and one-half negative, and the phase is dependent on the flowof current through the transformer primary-winding. At the same time,AC-power supplied from the power-lead 66 through the lead 551 isrectified through the diode 552, filtered through the filter networkcomprising the resistances 556 and 557 and the condensers 555 and S60,producing a direct-current voltage at the junction 558. Thisdirect-current voltage flows through the voltage-divider formed by theresistances 566 and 569 and then out through lead 300 into the secondaryof the coupling-transformer 302. The voltage-divider, by virtue of theratio of the resistance 569 to the resistance 566, produces abias-voltage which will go through the secondary-winding of thetransformer 302 and return to the base of the transistor 564; at thesame time, a considerably higher voltage is being applied to thecollector 563 through the resistance 557.

Now, the AC-signal applied into the coupling-trans former, due to theimbalance of the master-scale potentiometer 114 and thematerial-potentiometer 141, causes current to flow one way or anotherthrough the primarywinding, resulting in raisingor lowering thebias-voltage on the base of the transistor 564. In other words, thisinput from the coupling-transformer 302k either is added to orsubtracted from the actual DC-voltage biased onto the base of thetransistor 564, and thereby causes a greater or less flow of currentthrough the emitter 574, to ground. The more current that flows, themore the voltage will drop at the junction 561. Since, that voltage atjunction 561 is a fairly high value, it will fluctuate according to howmuch current is being drawn through the transistor 564, and as itfluctuates it supplies the coupling-condensers 588 and 5 89, which actas rectifiers and supply negative-voltage only to the bases 583 and 586of the relay transistors 584, 587. Any stray positive-current at thebases 583 and 586 is passed to ground through the diodes 592 and 593-,so that when current flows from the coupling-transformer 302 and thejunction 561, a pulsating-DC is applied to the bases 583, 586 of thetransistors 584 and 587. Since the phase of these pulses is dependent onthe direction of flow through the coupling-transformer 302, in onedirection the negative-pulses are in phase with the alternatelypulsating DC being supplied to the underweight-relay 304 and when in theopposite direction the phase of the input-voltage is shifted and is inphase with the supply-voltage of the overweight-relay 305. When thesupply-voltage to the collector of a transistor is inphase with theinput-voltage to its base, then an output is produced from thattransistor. The output-leads 613 and 614 may be connected to the relays304 and 303, respectively, and current is supplied to operate theserelays when the phase-relationship is present to produce an output fromone of the relay-transistors 584, 587.

To those skilled in the art to which this invention relates, manychanges in construction and widely differing embodiments andapplications of the invention will suggest themselves without departingfrom the spirit and scope of the invention. The disclosures anddescription herein are purely illustrative and are not intended to be inany sense limiting.

We claim:

1. An electronic sensing device for providing a signal responsive to thecomparison between two input signals, said device comprising: an ACpower transformer; an end tap connected to a power lead from each end ofsaid power transformer, said end tap power lead adapted to carry currentof opposite phase relationship; a rectifying means of opposite phasesensitivity in each of said power leads to form an intermittent pulsingvoltage of opposite phase in each power lead; each said power lead beingconnected to a relay-transistor; means to receive two separate inputsignals of alternating current to be compared in bucking-relationship,to produce a resultant alternating current; means to amplify saidresultant alternating current; means to filter out the positive pulsesof said alternating current; means to apply the negative pulses of saidamplified alternating current to the bases of said relay transistors;whereby the negative input impulse of said amplified alternatingcurrent, when applied to said transistors, will be in-phase with andmatch the intermittent pulses on one of the transistors depending on therelative strength of each bucking voltage, to produce an output currentfrom the in-phase transistor.

2. An electronic sensing device for providing a signal responsive to thecomparison between two input signals, said device comprising: a centralpower supply; two relay-transistors each having a base and a collector;connected to said central power supply; an AC power transformer, saidpower transformer having a grounded centertap and end power-leadsadapted to carry current of opposite phase-relationship; a rectifyingmeans of opposite phase sensitivity in each of said power leads to forman intermittent pulsing voltage of opposite phase in each power lead;each said power lead being connected to the collector of one of saidrelay-transistors; coupling-transformer means to receive two separateinput signals of alternating current supplied from said central powersup ply and connected to opposite ends of said couplingtransforrnerwinding in bucking-relationship, to produce a resultant alternatingcurrent output; means to amplify said resultant alternating currentoutput; means to filter out the positive pulses of said alternatingcurrent, means to apply the negative pulses of said amplifiedalternating current to the bases of said relay-transistors; whereby thephase of the output current from said coupling-transformer is dependenton the magnitude of the current at one end or another so that thenegative input impulse of said amplified alternating current output,when applied to said transistors, will be in-phase with and match theintermittent pulses on one of the transistors to produce an outputcurrent from the in-phase transistor and when the inputs to thecoupling-transformer are equal, no output will be produced on etiherrelay transistor.

No references cited.

ARTHUR GAUSS, Primary Examiner.

S. D. MILLER, Assistant Examiner,

U.S. DEPARTMENT OF COMMERCE PATENT OFFICE Washington, D.C. 20231 UNITEDSTATES ENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,404,288 October1, 1968 Jack D. Noble et a1.

It is certified that error appears in the above identified patent andthat said Letters Patent are hereby corrected as shown below:

In the heading to the printed specification, lines 5 and 6, "2024 10thAve. Oakland, Calif. 94606; said Noble assignor to said Fleming" shouldread Oakland, Calif.; said Fleming assignor to said Noble Signed andsealed this 17th day of February 1970.

(SEAL) Attest:

WILLIAM E. SCHUYLER, JR.

Commissioner of Patents Edward M. Fletcher, Jr.

Attesting Officer

